feat(5.21): Tasks Plugin — activities with status, priority, due dates, ARQ reminders

- New builtin plugin app/plugins/builtins/tasks/ with full CRUD
- Task model with TenantMixin (title, description, status, priority, due_date, assigned_to, contact_id)
- Routes: GET/POST /tasks, GET/PATCH/DELETE /tasks/{id}, POST /tasks/{id}/assign, POST /tasks/{id}/status
- All routes RBAC-protected (tasks:read, tasks:write, tasks:delete)
- ARQ cron job tasks_due_reminder (daily 8:00) sends notifications for due tasks
- Migration 0001_initial.sql creates tasks table with indexes
- Frontend: Tasks.tsx page with list, filter, create/edit modal, detail modal
- Frontend: api/tasks.ts with React Query hooks
- Route /tasks in routes/index.tsx, sidebar entry via plugin manifest
- i18n keys for nav.tasks and tasks.* in de.json and en.json
- Tests: test_tasks.py (11 tests) + Tasks.test.tsx (3 tests)
- Registered TasksPlugin in conftest.py and worker.py

app/plugins/builtins/tasks/routes.py

@@ -0,0 +1,145 @@
+"""Tasks plugin routes — CRUD, assign, status update."""
+
+from __future__ import annotations
+
+import uuid
+
+from fastapi import APIRouter, Depends, HTTPException, Query, Response, status
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.db import get_db
+from app.deps import get_current_user, require_permission
+from app.plugins.builtins.tasks import services
+from app.plugins.builtins.tasks.schemas import (
+    TaskAssignRequest,
+    TaskCreate,
+    TaskStatusRequest,
+    TaskUpdate,
+)
+
+router = APIRouter(prefix="/api/v1/tasks", tags=["tasks"])
+
+
+def _parse_uuid(val: str, field: str) -> uuid.UUID:
+    try:
+        return uuid.UUID(val)
+    except (ValueError, TypeError):
+        raise HTTPException(
+            400, detail={"detail": f"Invalid {field}", "code": "invalid_id"}
+        ) from None
+
+
+@router.get("", dependencies=[Depends(require_permission("tasks:read"))])
+async def list_tasks(
+    page: int = Query(1, ge=1),
+    page_size: int = Query(25, ge=1, le=100),
+    status: str | None = Query(None, pattern="^(open|in_progress|done)$"),
+    priority: str | None = Query(None, pattern="^(low|medium|high|urgent)$"),
+    assigned_to: str | None = Query(None),
+    contact_id: str | None = Query(None),
+    search: str | None = Query(None),
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """List tasks with filtering and pagination."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    return await services.list_tasks(
+        db, tenant_id,
+        page=page, page_size=page_size,
+        status=status, priority=priority,
+        assigned_to=assigned_to, contact_id=contact_id,
+        search=search,
+    )
+
+
+@router.post("", status_code=status.HTTP_201_CREATED, dependencies=[Depends(require_permission("tasks:write"))])
+async def create_task(
+    body: TaskCreate,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Create a new task."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    user_id = uuid.UUID(current_user["user_id"])
+    data = body.model_dump()
+    return await services.create_task(db, tenant_id, user_id, data)
+
+
+@router.get("/{task_id}", dependencies=[Depends(require_permission("tasks:read"))])
+async def get_task(
+    task_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Get a single task by ID."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    tid = _parse_uuid(task_id, "task_id")
+    result = await services.get_task(db, tenant_id, tid)
+    if result is None:
+        raise HTTPException(404, detail={"detail": "Task not found", "code": "not_found"})
+    return result
+
+
+@router.patch("/{task_id}", dependencies=[Depends(require_permission("tasks:write"))])
+async def update_task(
+    task_id: str,
+    body: TaskUpdate,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Update a task."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    tid = _parse_uuid(task_id, "task_id")
+    data = body.model_dump(exclude_unset=True)
+    result = await services.update_task(db, tenant_id, tid, data)
+    if result is None:
+        raise HTTPException(404, detail={"detail": "Task not found", "code": "not_found"})
+    return result
+
+
+@router.delete("/{task_id}", status_code=status.HTTP_204_NO_CONTENT, dependencies=[Depends(require_permission("tasks:delete"))])
+async def delete_task(
+    task_id: str,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Delete a task (soft-delete)."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    tid = _parse_uuid(task_id, "task_id")
+    deleted = await services.delete_task(db, tenant_id, tid)
+    if not deleted:
+        raise HTTPException(404, detail={"detail": "Task not found", "code": "not_found"})
+    return Response(status_code=status.HTTP_204_NO_CONTENT)
+
+
+@router.post("/{task_id}/assign", dependencies=[Depends(require_permission("tasks:write"))])
+async def assign_task(
+    task_id: str,
+    body: TaskAssignRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Assign a task to a user."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    tid = _parse_uuid(task_id, "task_id")
+    assigned_to = _parse_uuid(body.assigned_to, "assigned_to")
+    result = await services.assign_task(db, tenant_id, tid, assigned_to)
+    if result is None:
+        raise HTTPException(404, detail={"detail": "Task not found", "code": "not_found"})
+    return result
+
+
+@router.post("/{task_id}/status", dependencies=[Depends(require_permission("tasks:write"))])
+async def update_task_status(
+    task_id: str,
+    body: TaskStatusRequest,
+    db: AsyncSession = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Update task status."""
+    tenant_id = uuid.UUID(current_user["tenant_id"])
+    tid = _parse_uuid(task_id, "task_id")
+    result = await services.update_task_status(db, tenant_id, tid, body.status)
+    if result is None:
+        raise HTTPException(404, detail={"detail": "Task not found", "code": "not_found"})
+    return result